Activated-sludge treatment.



Bpeclflcatlonof Letterihteut.

Io Drawing.

' a citizen of the United States, residing at Chicago, in the county of Cook and State of Illino s, have inventedoertain new and useful Improvements in Activated-Sludge Treatment, of which the following is a specification. I

Thei'activated sludge method of sewage disposahjthough of comparatively modern I origln'and' in its infancy, is one which is well known and constitutes a, fieldof activity for sanitary'engineers in the efiort to surmount resent difliculties in its application to a wi er'range of usefulness and in experi- -mentation to increase its efficiency and economical availability,

I Briefly andgenerally stated, theactivated sludge treatment of sewage consists in conducting the raw sewage into and through aerating tanksrovided with means fort e introduction 0 air under pressure to the bottom ofthe tank, whereby the air is caused to bubble upthrough the liquid sewage. The passage of the air through the sewage develops. in time microscopic aerobic organ isms which in the course of their growth or by means of conditions provided by their growth, oxidize: the colloidal and soluble solids in the sewage causing them to separat'eout as flocculent particles. The treated sewage,'at,the proper stage is run into a settling" tank where it is allowed to remain quiescent for from thirty minute's'to one hour, and'the solids settle to'the bottom as 'a flocculent ooze, called activated sludge.

The remaining liquid content of the sewl age is' rendered perfectly clear, white and odorless. This eflluent liquid may thenbe runjoif through. thesewers to rivers or other natural channels without injury to fish or menace tothe health or comfort of people livingadjacent thereto. v

The activated sludge is removed from the bottom of the tank, to be freed of its water content, and when dried is available as-a fertilizer, containing a large percentage of am.-

from. any oflensiveodors.

To make the process con ASSIGNOB 'ro ARMOUR urn contrast; or CHICAGO, mmnoxs, a conroaa'rxon or rumors.

Application file d July 9, 1917. Serial No. 179,457.

' 7 previously treated, whereby the process is B. MULLQY, v

to a few hours.

age such as thatresultingl houses is accompanied wit panied by the disadvantage of its also that o multiplying the quan onia compounds and being practically free I tinuous and or: .der to hasten thie treatment of thej'raw sewa u manta is; 1 61 reduced in pointof time from several days The ap lication of'this activated sludge method o sewage disposal to industrial sewfrom packingv l d fl ties which have heretofore militated against its general adoption, it having been mindthat the operation of the method as worked out in connection with the disposal of do"-' 05 mestic or municipal sewage-does not in all respects follow when the system is applied to the more highly concentrated sewagere sultin from the packing industry. 7 a

Pacing house sewage originates from 710. many and varied departments; such as the abattoirs, the power plant, the lard refinery, the oleomarga'rimcanning, curing and sau a sage de artme'nts,' he rendering tanks, and the fertilizer plants; as well as manyother smaller departments, together with the mestic sewage of many. thousands of eniployees. The resultant composite sewage'is much more concentrated than the ordinary 'domestic sewage and contains approximately four to twenty times .as much suspended solids, averaging about 500.60" y parts suspended solids in 1,000,000. These suspended solids consists largelyof organic eb riali I T It is found that wherethisraw sewa its concentrated state is inoculated as" ters the aerating-tank byrmeans' ofacti sludge resulting, from the aerati" of vious quantities of sewage, the h of concentration is such that the't not as eflicient as where the same are applied to the morehighly dilutedd mesticsewa e. 5

The dilution of the raw; sewage of water to reduceits consistency .a large sup ly of water forthelp W t L has mid to be handled and crease in the volume of material undergoin treatment and also utilizing the vitality 0 the eflluent liquid to assist t e inoculation of the fresh sewage, so that the time of aera- 5 tion in the activated sludge process is thereby greatly shortened.

I claim: The im rovemcnt in the activated sludge method 0 treatment as applied to industrial 10 sewage which consists in preliminary dilutmums ing the raw sewa with efliuent liquid from previously treate sewage.

In testimony whereof I have hereunto signed my name in the presence of two subscribing witnesses.

' GEORGE B MULLOY. Witnesses:

A. B;A. WALTON, E. G. MCDONALD. 

